tclreadline breaks line continuation with backslash at the end

[jlombera]

Problem

\<newline> line continuation is broken when tclreadline is used. Both in tclsh8.6 and tclsh9.0. E.g:

$ tclsh8.6
tclsh8.6 [~] info \
unknown or ambiguous subcommand "\": must be args, body, class, cmdcount, commands, complete, coroutine, default, errorstack, exists, frame, functions, globals, hostname, level, library, loaded, locals, nameofexecutable, object, patchlevel, procs, script, sharedlibextension, tclversion, or vars
while evaluating info \
tclsh8.6 [~]

$ tclsh9.0
tclsh9.0 [~] info \
unknown or ambiguous subcommand "\": must be args, body, class, cmdcount, cmdtype, commands, complete, constant, consts, coroutine, default, errorstack, exists, frame, functions, globals, hostname, level, library, loaded, locals, nameofexecutable, object, patchlevel, procs, script, sharedlibextension, tclversion, or vars
while evaluating info \
tclsh9.0 [~]

Whereas without tclreadline, line continuation works as expected:

$ tclsh8.6 
% info  \
patchlevel
8.6.17
% 

Even rlwrap(1) works:

$ rlwrap tclsh8.6 
% info \
patchlevel
8.6.17
% 

System info

OS: Debian GNU/Linux forky
Tcl version: tcl8.6.17/tcl9.0.3 (packaged by Debian (tcl8.6/tcl9.0))
tclreadline version: 2.4.1 (packaged by Debian (tcl-tclreadline))